The carrier puts all sorts of stupid little fine print in its ads, trying to legally indemnify itself against the fact that its current 4G claim is totally worthless. But that doesn’t balance out the fact that these phones are being advertised with 4G in the name, and if you stand in the same place with a “4G” phone and a “3G” phone on the same network, the 3G phone will be faster.
AT&T is late to this fake 4G game and far behind the others in the US. No one has real 4G, but everyone is claiming to have it. In some cases 3G phones have faster connectivity than 4G ones. Go figure.